Insertion head with a twisting device for electrical components

ABSTRACT

A turret-like insertion head having at least one twisting device for mounting electrical components. The insertion head has a stator, a rotor and an optical measuring device. A plurality of circularly distributed grippers are mounted on the rotor such that the grippers can rotate about a mounting axis. The optical measuring device detects the position of the components held on the grippers, and as a result, a component can be twisted into its approximate mounting position during forward movement of the gripper before making a final position measurement, thereby saving time.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an insertion head having at least onetwisting device for electrical components, the turret-like insertionhead having a stator and a rotor, on which a large number of circularlydistributed grippers are mounted such that they can rotate about amounting axis, the insertion head having an optical measuring device fordetecting the position of the components held on the grippers, and itbeing possible for the components to be twisted accurately into therequired mounting position by a precision twisting device after beingmeasured optically.

2. Description of the Related Art

European Patent Document EP-C 0 315 799 discloses providing an insertiondevice with a moveable turret head, in which the grippers provided withsuction pipettes are arranged on a rotor such that they stand out instar fashion. A stator of the insertion head is provided with processingstations distributed circumferentially.

It is usual to design one of these stations as an optical measuringstation, in which the rotational position of the component previouslypicked up is determined. In a subsequent twisting station, the positionof the component is changed in accordance with the desired installationposition. This change includes a coarse twist, for example in 45° steps,corresponding to the desired installation position, and precisiontwisting, by means of which the fetching-in accuracy in picking up thecomponents from a feed device is compensated for.

In addition, it is usual to provide the gripper with a disk-like slewingring of relatively great diameter. On said ring, a friction wheel of thetwisting device can be placed radially, whereupon the twisting device isactivated and exact twisting of the gripper through a precalculatedangle is effected. Since the components are to be placed onto theprinted circuit board in different installation positions, the twistingangle may be so large that the entire twisting cycle lasts longer thanthe operating cycles on other stations of the turret head, whichaccordingly limits its insertion performance.

SUMMARY OF THE INVENTION

The invention is based on the object of reducing the time loss whentwisting the grippers.

This object is achieved by the invention of an insertion head having atleast one twisting device for electrical components, the turret-likeinsertion head having a stator and a rotor, on which a large number ofcircularly distributed grippers are mounted such that they can rotateabout a mounting axis, the insertion head having an optical measuringdevice for detecting the position of the components held on thegrippers, it being possible for the components to be twisted accuratelyinto the required mounting position by a precision twisting device afterbeing measured optically, wherein, before being measured, the componentscan be twisted into a position approximating the mounting position bymeans of a coarse twisting device.

The rotation of the gripper is now distributed to two stages, the coarsetwisting being carried out quickly without particular accuracy in atwisting segment before the optical measuring device. As a result, evenin the case of a large overall twisting angle, the twisting angle in theprecision twisting device can be shortened to such an extent that theprecision adjustment does not last longer than, for example, than theoptical measurement in the measuring device.

Advantageous developments of the invention provide that the rotor can betwisted step by step with respect to the stator, the optical measuringdevice is designed as a measuring station, and the precision twistingdevice is designed as a precision twisting station anchored to thestator. Specifically, the coarse twisting device anchored to the statoris designed as a coarse twisting station associated with a holdingstation for the grippers. The gripper having a slewing ring, which canbe brought peripherally into frictional engagement with at least onefriction surface on the twisting device, it being possible for thefriction surface to be placed on the slewing ring in the radialdirection and it being possible for the gripper to be twisted by meansof a tangential relative movement between the twisting device and theslewing ring, wherein the stationary friction surface of the coarsetwisting device extends along the movement path of the gripper that canbe twisted together with the rotor, and the rolling length on thefriction surface can be varied by means of the controlled feed of thefriction surface onto the slewing ring. In one embodiment, the coarsetwisting device permits a rotational adjustment of the gripper in coarsebasic steps. The friction surface is formed on a radially adjustablefriction block that is anchored to the stator. The segmented frictionsurface is formed by a plurality of individually adjustable frictionblocks, whose frictional length corresponds to the rotational angle of abasic step. Preferably, the friction surfaces are shorter than thedistance between two of the mutually adjacent slewing rings.

The development providing that in that the rotor can be twisted step bystep with respect to the stator, the optical measuring device isdesigned as a measuring station, and the precision twisting device isdesigned as a precision twisting station anchored to the stator meansthat the measurement and the precision twisting of the components takeplace at a standstill.

The measuring station and precision twisting station, and also thecoarse twisting station which is anchored to the stator and associatedwith a holding station for the grippers are fixed to the stator in asimple way and can enter into a precise operative connection with thecomponent or with the gripper.

By means of the frictional surface on the twisting device which extendsalong the movement path of the gripper that can be twisted together withthe rotor and in by which the rolling length on the friction surface canbe varied by means of the controlled feed of the friction surface ontothe slewing ring, the coarse twisting is carried out without any timeloss during the forward movement of the gripper which is required in anycase. The stationary friction surface can be formed on a simpleconstructional part, on which the slewing ring rolls until the desiredend position has at least approximately been reached. The length of theengagement between the friction surface and the slewing ring can beterminated accurately by means of a radial feeding movement of thetwisting device, for example with the aid of piezoelectric driveelements with a short reaction time, so that the gripper can be twistedthrough the calculated angle.

The development in which the coarse twisting device permits a rotationaladjustment of the gripper in coarse basic steps makes it possible tocarry out the coarse twisting with little control effort.

The friction block in which the friction surface is formed on a radiallyadjustable friction block that is anchored to the stator constitutes asimple component which is easy to operate.

The development that the segmented friction surface is formed by aplurality of individually adjustable friction blocks whose frictionallength corresponds to the rotational angle of a basic step makes itpossible to design the length of the friction surfaces in such a waythat a twisting angle of 45°, for example, is achieved at the gripper ineach case. Multiplication of the twisting angle is made possible by anappropriate number of adjustable friction blocks which can be switchedinto the movement path of the slewing ring.

The development that the friction surfaces are shorter than the distancebetween two of the mutually adjacent slewing rings ensures that thegrippers with the stewing rings can be moved along a precisely definedpath. For example, in the case of a stepper-like turret head withradially projecting grippers, the slewing rings move in one plane, sothat the friction blocks can also be arranged in one plane, which isassociated with mounting advantages. Shortening the frictional lengthensures that each friction surface is in each case occupied by only onestewing ring. As a result, the latter can be twisted differently andindividually, as predefined.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following text, the invention will be explained in more detailusing an exemplary embodiment illustrated in the drawing.

FIG. 1 shows a side view of an insertion head for populating electricalprinted circuit boards with components, and

FIG. 2 shows a different side view of the insertion head according toFIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

According to FIGS. 1 and 2, a turret-head-like insertion head 1comprises a stator 2 and a rotor 3. The insertion head can be moved overa printed circuit board 4 and has grippers 5 which project radially in astar-like manner and are provided with suction pipettes, at whose freeends electrical components 6 are held. The rotor can be rotated step bystep through an index angle, which corresponds to the pitch angle of thegrippers 5. The grippers 5 can be pushed telescopically out of therotor. The gripper 5 located in the mounting position in each case cantherefore place the component 6 on the printed circuit board 4 in thevertical arrow direction shown.

The rotatably mounted grippers 5 are provided with slewing rings 7shaped like disks. An optical measuring station 8 is used to measure theposition of the components 6 with respect to the gripper 5. Fitted tothe stator 2, along the movement path of the slewing rings 7, arefriction blocks 9, which can be deflected in the horizontal arrowdirection to such an extent that their friction surfaces 14 can beplaced on the slewing rings 7. When the rotor 3 is twisted, the slewingrings 7 therefore roll with their outer surfaces on the frictionsurfaces 14 and are accordingly twisted. This twisting takes place in atime-saving manner between the holding stations of the rotor 3. Thelength of the friction blocks 9 is such that the grippers 5 are in eachcase twisted through 45°, for example.

By switching the braking-block feed on and off, the gripper can betwisted by any desired multiple of the coarse twisting angle. Followingthis coarse twisting, the components 6 are measured in the opticalstation, and their deviation from the installation position isdetermined. A subsequent precision twisting device 10 is associated withone of the holding stations. In said device, the rotational position ofthe gripper 5 can be changed in fine steps, and the desired installationposition of the component can also be corrected.

The friction blocks 9 are part of a coarse twisting device 11 and areconnected to the latter via piezoelectric drive elements 12, whichadjust the friction block 9 in the direction of the slewing ring 7.

Instead of the coarse twisting device 11 with the friction blocks 8, acoarse twisting station (13), indicated by dash-dotted lines, can alsobe arranged on the stator of a holding station of the grippers 5, beingof the same construction as the precision twisting station 10.

Although other modifications and changes may be suggested by thoseskilled in the art, it is the intention of the inventors to embodywithin the patent warranted hereon all changes and modifications asreasonably and properly come within the scope of their contribution tothe art.

1. A device for mounting electrical components, the device comprising aturret-like insertion head having at least one precision twistingassembly, a coarse twisting assembly, a stator, and a rotor including aplurality of circularly distributed grippers for holding the componentsto be mounted, the rotor being disposed for rotation about a mountingaxis, and the insertion head further having an optical measuring devicefor detecting a position of components held by the gripper, whereby thecomponents to be mounted are twisted into a position approximating adesired mounting position by the coarse twisting assembly before beingoptically measured, and the components to be mounted are accuratelytwisted into the desired mounting position by the precision twistingdevice after being optically measured.
 2. The device as claimed in claim1, wherein the rotor can be twisted step by step with respect to thestator, the optical measuring device serves as a measuring station, andthe precision twisting assembly serves as a precision twisting stationanchored to the stator.
 3. The device as claimed in claim 2, wherein thecoarse twisting assembly anchored to the stator serves as a coarsetwisting assembly associated with a holding station for the grippers. 4.The device as claimed in claim 3, wherein the gripper includes a slewingring which can be brought peripherally into frictional engagement withat least one friction surface on the coarse twisting assembly and theprecision twisting assembly, and the frictional surface is placed on theslewing ring in a radial direction such that the gripper to be twistedin a tangential relative movement between the coarse twisting assembly,the precision twisting assembly and the slewing ring, whereby thefriction surface of the coarse twisting assembly extending along themovement path of the gripper can be twisted together with the rotor andthe rolling path on the frictional surface can be varied by a controlledfeed of the friction surface onto the slewing ring.
 5. The device asclaimed in claim 4, wherein the coarse twisting device permits arotational adjustment of the gripper in coarse basic steps.
 6. Thedevice as claimed in claim 4, wherein the frictional surface is formedon a radially adjustable friction block anchored to the stator.
 7. Thedevice as claimed in claim 5, wherein the friction surface is formed bya plurality of individually adjustable friction blocks, whose frictionallength corresponds to the rotational angle of a basic step.
 8. Thedevice as claimed in claim 6, wherein the adjustable friction blocks areshorter than the distance between any two mutually adjacent slewingrings.